Fluid pump



Dec. 18, 1951 M. H SCHERGER ErAL 2,578,746

FLUID PUMP Filed Dec. 12, 1946 Patented Dec. 18, A1951 UNITED .STATESPATENT OFFICE VFLUID PUMP 1' Milton H.v Sch-erger` and Earl BJ Terrill,Jr., Chicago,` Ill., assignors itc Mills industries, Incorporated,Chicago, Ill., a corporation of vIllinois Application December 12, 194B,Serial N o. 715,748

. 3-Claims. (Cl. ID3-44) This invention relates to" pumps ofl thetypeused for pumping -a liquid or other iiuid and more particularly to apistonpump in "which a diaphragm is employed in conjunction with-,a bodyof oil or other hydraulic fluid between the piston and the diaphragm.

Anv important object of Vthe inventionis the provision in such a pump ofmeans for controlling the quantity and conditionl of the contents ofthehydraulic liuid chamber so'that the pump will be automaticallymaintained at maximum efliciency over a long period of time.

To this end provision is made for replacing any liquid that may yescapefrom said chamber and for eliminating any excess liquid or air `that maygain admission to the chamber, al1 -without human intervention or thenecessity .of stopping the operation of the pump tocorrect any improperconditions.

A further object is to provide a pump for this purpose which is soconstructed that the diaphragm will notk be subject to as much strainasin the usual diaphragm pump construction and therefore will notrequire frequent, if any, repair or replacement during the life of thepump.

Another object is to provide a pump without a stuiing box or rotary sealwhich will nevertheless handle corrosive or valuable fluidsautomatically without loss of such-fluids.

Other objects and advantages of theinventionwill be apparentfrom thefollowing description and accompanying drawing in which the single viewis a cross section of a'uid pump in which the principles of theinvention are embodied.

In the embodiment of the invention shown in the drawing the numeral I Iindicatesa crankcase, which preferably is arranged in horizontalposition and is supported by anend member I2 having a horizontal portionI3 resting lupon any suitable supporting base. y

The crankcase is formedto provide acylinder I4 at one end thereof linwhichal plston'lis reciprocably mounted, 4said piston being vconnectedby the usual connecting rod I6 with va crank I'I on a crank shaft I8adaptedfto be driven'from 'any suitable source of power. The crankcasecontainsY a body of oil," 'lndicatedby the numeral -I 9, and` when .thecrankca'seisdisposed in horizontal position, ,as shown, the bottom oil`sump side-portion lthereof will provide an in which said oil iscontained.

-A pumpchamber' 2l :is provided. beyond-the.'` head of the Vpistonby-meansf" of `an .enlarged cylinder head 22 and a .cap'231 securedtheretov by screws 24.

The outer face of said cylinder head or block y 22 is of concave ordished formation, as indicated at 25, and the central part thereof is inthe form of a grid having openings 26 therein communieating with thespace 2l in the cylinder beyond the head of the piston I5.

The inner face of the cap 23 is also of concave or dished formation, asindicated at 28, the concavity therein complementing the concavity inthe cylinder head 25 so as to form a chamber of generally ellipticalshape, with the opposed faces thereof sloping gradually from theperipheral portions of the cylinder head and cap, the inner faces ofwhich are preferably at.

A diaphragm 29 made of rubber sheeting, or other suitable material, istightly clamped between the peripheral portions of the cylinder head 22and cap 23 by the screws 24 and extends vertically across the center ofthe chamber 2I when the piston is in its central position.

The space between the head of the piston I5 and the diaphragm 29 is lledwith a suitable hydraulic uid, such as oil, and the space on theopposite side of the diaphragm is adapted to l receive the liquid orother fluid to be pumped.

Such fluid is drawn into the latter space through an intake pipe 3Iconnecting with an intake check valve 32 communicating with passages 33extending through the cap 23 into which said check valve is screwed, orotherwise suitably attached. Said valve includes a disc 34 normally heldin engagement with a valve seatV 35 by means of a spring 35, said valvedisc being adapted to be unseated against the tension of said springwhen a vacuum is created in the pumping chamber upon the suction strokeof the piston which draws the diaphragm to its innermost positionagainst the face 25.

A discharge check valve 31 is provided in the cap 23 on the oppositeside from the intake valve 32- and' communicates with an outlet pipe 38.

. Said discharge valve includes a valve disc 39 normally heldV against avalve seat 4I by means of aspring 42. Communication is provided betweenr: the pumping chamber 2I and the'valve 31 by passages 43 extendingthrough the cap 23 and the pumped uid is forced out through saidpassages and said discharge valve upon the compression stroke of thepiston which unseats the l valvedisc 39 in obvious manner.

each compression stroke ofk the piston, thedia- 3 phragm being actuatedthrough the medium of the hydraulic iiuid in the space between thepiston and said diaphragm.

In case of loss of hydraulic fluid from said space by leakage past thepiston I5, or otherwise, the lost fluid will be replaced by fluid drawnfrom the oil sump in the crankcase through a conduit 44 extending fromsaid sump to yan oil` check valve 45 which in turn communicates with thespace 21 through a hole 46 extending radially through the cylinder head22. Said oil check valve may be of the ball type with a ball 41 normallyheld against a seat 48 by means of a spring 49. The inner face 25 of thepump chamber limits the inward movement of the diaphragm and, in case ofany shortage of hydraulic fluid in the space between the piston and thediaphragm, further movement of the piston on the suction stroke willcreate a vacuum in said space which will result in the unseating of thevalve 41 and the drawing of suicient oil from the crankcase tocompletely ll the hydraulic fluid space.

Any loss of iiuid from said space can only be between the piston and thecylinder wall, in which case it will be returned to the crankcase sothere will be no loss of fluid from the pumping system.

It is possible that some air or excess oil might bedrawn into the spacebetween the piston and the diaphragm on the suction stroke of the pistonunder centain conditions and we provide means for bleeding olf such airor excess oil, which means will now be described.

A metering valve 5I is provided in the periphl ery of the cylinder head22 and provides intermittent communication between the pumping chamberand the crankcase with which said valve is connected by means of aconduit 52. A passageway 53 leads from the high point in the pumpingchamber 2| to a reservoir 54 formed in the cylinder head inwardly fromsaid metering valve 5I, and an oil hole 55 extends from the space 21 inthe cylinder to said reservoir.

The valve 5l comprises an outer shell 55 screwed into the cylinder head22 and having plugs 51 and 58 screwed into the interior thereof, withpacking rings 59 and 6I interposed between said'shell and plugs.

seat 63 is provided on the bottom of the outer plug 51. A passageway 64extends through the plug 58 and the plug 51 has passageways 65 and 56therein through which fluid may pass when permitted by the action of thevalve. A central partition 51 extending horizontally between the wallsof the shell 56 has passageways G8 therein and is interposed betweenvtwovalve discs 69 and 1l Vcarried on a stem4 12', which is mounted in acentral opening in said partition 5 1. Said discs 69 and 1| are normallyheld in their lowermost position by means of a spring 13 mounted on theupper end of said stem 12 and located in a cavity 14 in the plug 51,said spring bearing against a lock nut 15 above the disc 1I. The springthus holds the disc 59 normally in contact with the seat 62, with thedisc 1| unseated.

Upon the compression stroke of the piston the valve disc 69 will beunseated and the disc 1l will be seated. Thus as one part of the lvalveopens the other is moved to closed position, and the reverse actiontakes place on the return stroke of the piston. On the compressionstroke any air or gas collected at the top of the pump- A valve seat 62is pro-v vided on the top of the inner plug 58 and a valve ing chamberwill be forced into the space 54 and, on succeeding strokes, into thespace 16 between the /two parts of the valve. If no air or gas ispresent in the top of the pumping chamber a small amount of oil will bebled off on. each stroke, the amount not being enough, however, tomaterially impair the efficiency of the Pump- J Since the-*valve disc 1Iwill be rapidly seated against the seat B3 only a very small amount ofgas or oil (perhaps less than a drop in the case of oil) will be bled oneach stroke. The continuous bleeding, however, is suicient to dispose ofany air or oil that may leak past the piston or to purge any air or gaswhich may be present in the hydraulic uid chamber when the pump n isfirst put into operation.

It will now be apparent that provision has been made for automaticallymaintaining the proper quantity and conditionof the hydraulic fluid andfor preventing undue wear on the diaphragm so that the pump will operatewith high eiciency for along period of time without requiring anyservicing Vor the replacement or adjustment of any of the parts.Furthermore a pump constructed as herein described' is adaptable to awide Variety of suction and discharge pressure applications for whichprevious constructionsv have not been well adapted.

- The foregoing detailed description has been givenfor clearnessvofunderstanding only, and no unnecessary limitations should be understoodtherefrom, but the appended claims should be construed as broadly aspermissible in view of the prior art.

lWe claim:

l. A pump for liquids or other fluid, comprising a cylinder, apistonreciprocably mounted in said cylinder, a crankcase containing an oilsump and having a crankshaft mounted therein operativelyyconnected withsaid piston, a pumping chamber beyond the head of the piston, adiaphragm mounted in a midposition in said chamber,'the space betweenthe diaphragm and the piston being adapted to receive a hydraulic fluidand the space on the opposite side of the diaphragm being adapted toreceive a fluid to be pumped, intake and Outlet passages for the pumpedfluid communicating with the latter space, a one-way conduit betweensaid hydraulic fluid space and said oil sump whereby oil may be drawnfrom kthe latter on the suction stroke of the piston in casey of adeciency in the quantity' of the hydraulic uid in said hydraulic uidspace, and means for bleeding from said hydraulic fluid space upon thecompression stroke ofsthe piston, any gas which may accumulate in saidhydraulic fluid space, said last-mentioned means comprising a secondconduit between the high point in said hydraulic'fluid space and saidcrankcase and ametering valve in said second conduitconstructed andarranged to momentarily open on such compression stroke of the piston tobleed 'a small amount of gas from such hydraulic fluid space on eachsuch stroke.

`2. A pump for liquids or other uid, comprising a cylinder, a pistonreciprocably mounted in said cylinder,.a crankcase containing an oilsump and having a crankshaft mounted therein operatively connected withsaid piston, a pumping chamber beyond the head of the piston, adiaphragm mounted in a midposition in said chamber, the space betweenthe diaphragm and the piston being adapted to receive a hydraulic fluidand the space on the opposite side of the diaphragm being adapted toreceive a uid to be pumped, intake and outlet passages for the pumpedlluid communicating with the latter space, a one-way conduit betweensaid hydraulic uid space and said oil sump whereby oil may be drawn fromthe latter on the suction stroke of the piston in case of a deficiencyin thel quantity of the hydraulic fluid in said hydraulic uid space, andmeans for bleeding from said hydraulic fluid space upon the compressionstroke of the piston, any gas which may accumulate in said hydraulicfluid space, said last-mentioned means comprising a second conduitbetween said hydraulic fluid space and said crankcase and a meteringValve in said second conduit, said metering valve comprising a two-seatvalve adapted to momentarily open on such compression stroke of thepiston to bleed a small amount of gas from the hydraulic uid space oneach such stroke.

3. A pump for liquids or other fluid, comprising a cylinder, a pistonreciprocably mounted in said cylinder, a crankcase containing an oilsump and having a crankshaft mounted therein operatively connected withsaid piston, a pumping chamber beyond the head of the piston, adiaphragm mounted in a midposition in said chamber, the space betweenthe diaphragm and the piston being adapted to receive a hydraulic fluidand the space on the opposite side of the diaphragm being adapted toreceive a iluid to be pumped, intake and outlet passages for the pumpedfluid communicating with the latter space, a one-way conduit betweensaid hydraulic fluid space and said oil sump whereby oil may be drawnfrom the latter on the suction stroke of the piston in case of adeciency in the quantity of the hydraulic uid in said hydraulic uidspace, and means for bleeding from said hydraulic iluid space upon thecompression stroke of the piston, any gas which may accumulate in saidhydraulic fluid space, said last-mentioned means comprising a secondconduit between said hydraulic fluid space and said crankcase and ametering valve in said second conduit, said metering valve comprising amovable element having two spaced discs thereon, and a valve blockhaving passageways for the fluid therein, said block having two spacedvalve seats adapted to be engaged by said discs, respectively, onethereof being normally seated, one of the discs being unseated when theother is seated and both discs being momentarily unseated upon thecompression stroke of the piston whereby a small amount of gas will bebled through said valve upon each such stroke.

MILTON H. SCHERGER. EARL B. TERRILL, JR.

REFERENCES CITED The following references are of record in the WarrenJuly 29, 1947

